Line-at-a-time printer



Nov; 12, 1963 K. SCHEFFEL LINE-AT-A-TIME PRINTER Filed Nov. 6. 1961 I N VEN TOR.

Kurt Scheffel 0 [24% Attorney United States Patent 3,110,251 LlNE-AT-A-TIME PRENTER Kurt Schetfel, Aulendort, Wurttemberg, Germany, as-

siguor to International Standard Electric Corporation,

New York, N.Y., a corporation of Delaware Filed Nov. 6, 1%1, Ser. No. 150,456 Claims priority, application Germany Nov. 18, 1960 4 Claims. (Cl. 101-93) This invention relates to a line-at-a-time printer employing type rings, and in which the printing is effected in the normal position.

Various types of line-at-a-time printers have already become known. One type operates with type bars or type wheels. In order to effect the printing, all type carriers are set, and the actual printing is carried out in the normal position, in that either the type carriers hit the paper, or in that hammers are struck from behind against both the paper and the type carriers. In the case of on-the-fiy printing devices, the printing hammers are struck in the correct moment during the continuous rotation of the type Wheels. This last mentioned type of rinting device, aswill be easily understood, requires a complicated control mechanism, and on the other hand devices of this type also tend to produce a blurred print because in each case, during the printing, there is a relative movement vertically in relation to the line between the printing type and the paper. As opposed thereto, the first mentioned type of printing device operates substantially slower, because at first all type carriers have to be set, and the printing can only be effected thereafter; this method, however, provides a substantially better face of the resulting print. Efforts have therefore been made to find an optimum way, that is, a high-speed printing device, which produces an acceptable face of print.

As a result of these efforts line-a-t-a-time printers with type rings have become known, in which the type rings are arranged on a permanently rotating shaft, and are taken along by friction. This has the advantage that the entire driving mechanism does not need to be stopped for every printing operation and re-accelerated to reassume the full rate of speed thereafter, but this also has the disadvantage that the stoppage of the type rings produces a considerable heat. On the other hand, the control of the printing operation is rendered rather diflicult, and the locking device for stopping the respective type rings requires relatively much space, so that the full width of the type rings cannot be utilized for the printing purpose.

The novel type of linesat-a time printer of the invention uses type rings that are loosely seated on a common driving shaft in the conventional manner, and the printing is performed in the normal position. For avoiding the aforementioned disadvantages, however, the invention proposes the type rings to be arranged on a magnetic shaft, so that the coupling of the type rings will be effected by magnetic force. The type rings are designed as toothed wheels, and to each toothed type-wheel there is assigned a toothed ratchet wheel rolling thereon, capable of being blocked with the aid of a stationary ratchet pawl arranged in the apparatus, so that the type ring also is prevented from performing its further rotation, but is ready to perform the printing operation.

The fact that the type rings are driven by magnetic force has the advantage that the type wheels do not need to be seated frictionally on the driving shaft, but can be seated rather loosely, thus causing the heat development during the stoppage to be considerably lower than with the conventional types of line-at-a-time printers. The individual toothed ratchet wheels have the advantage, firstly of having no effect on the width of the printing types and, secondly, of being suitable themselves for controlling "ice the type rings, i.e. for actuating the ratchet pawl. It is appropriate to design the ratchet wheels as code disks in the conventional manner with the code marking being used to control the ratchet pawl, e.g. by energizing an electromagnet in the presence of the respective code combination for operating the ratchet wheel; to this end it is possible to use the armature of the electromagnet itself. This, in turn, has the advantage of making impossible any faulty control operations with respect to time and, consequently, any faulty settings, and moreover, of requiring no resetting of the type rings to the initial positions subsequently to the performance of the printing operation.

In the following the invention will now be explained in detail with reference to FIGS. 1 and 2 of the accompanying drawings, in which:

FIG. 1 shows a partial section of the high-speed lineat-a-time printer with a view of several type rings and associated ratchet wheels, and

FIG. 2 is a sectional view of the line-at-a-time printer according to the invention.

The type rings 1 (FIGS. 1 and 2), whose widths correspond to the spacing between the letters, are arranged closely to one another on the electromagnetic driving shaft 2 which is rotatably arranged within the support-ing frame. The electromagnetic driving shaft 2 which is permanently driven by a motor, is electrically energized via the leads 3 led through the hollow driving pivots 4. The .type rings 1 are arranged in an easily rotatable manner on the electromagnetic driving shaft 2, so that there is only a slight mechanical friction. Along their circumference the type rings 1 are provided with e.g. 36 embossed printing types 5 leaving a small tooth gap 6 between the individual types.

The tooth gaps 6 on the type rings 1 are engaged by the teeth 7 of the ratchet wheels 3, each type ring having its individual ratchet wheel. These ratchet wheels 8 are seated in an easily rotatable manner on the three shafts 9, 10, 11 which are firmly arranged within the supporting frame. The mutual spacing between the Wheels is secured by the length of their hubs 12. On the same shafts 9, 10, 11 the brush-holding levers 13 are still arranged between the ratchet wheels 8.

On one side the ratchet wheels 8' are provided With a pulse-transmitting disc 14 which may he designed e.g. in accordance with the known printed circuit technique. This disk may also be a copper disk in which the currentless or electrically inactive sections of the slip rings are etched away and filled with a sealing compound (casting resin). The conducting surfaces of this pulsetransmitting disk 14, for example, are connected to ground. The brushes 15 are arranged to contact with the slip rings and are mounted via the block of insulating material 16 on the brush-holding levers 13. The brushholding levers 13 together with the block of thein-sulating material 16 and the brushes 15 are capable of being readjusted by some angular degrees about the shafts 9, 10 and 11, and are capable of being fixed in the adjusted or set position with the aid of clamping devices (not shown). In this way the brushes can be adjusted in accordance with the operating time of the locking magnets Furthermore, the locking magnets 17 are staggered and graded in echelon formation around the ratchet wheels 8. The locking armatures (ratchet pawls) 18 of these magnets are arranged in front of the teeth 7 of their respective ratchet Wheels 8 in such a way that these armatures, upon energization of the locking magnets 17, will engage the tooth gaps, and the next tooth 7 of a particular ratchet Wheel will come to lie close to its associated locking armature 18, so that in this way the ratchet wheels 8 are prevented from performing a further rotation. The two pole pieces 19 and 21} which are designed as bars and extend over the entire group of type rings, constitute the poles of a closed magnet system, whose coils 21 and 22 may also be arranged at the two face sides. The ends of the poles are positioned exactly opposite the types and thus serve as magnetic aligning beams.

The paper or blank 23 to be printed is positioned between the ink ribbon and the printing beam 25. Instead of the ink ribbon 24 extending in the axial direction of the electromagnetic driving shaft 2 an ink pad (inking cloth) may also be used having the same width as the group of type rings, and extending from the denoted coil 26 to coil 27, and also being provided with one of the conventional types of ink-ribbon feed and reversing mechanisms.

F or selecting the desired character, a relay circuit for example, is used to which the connecting terminals of the locking magnets 17 are led, as well as the connecting terminals of the brushes 15, and of the input device which has not been shown (keyboard, storage, perforated-type reader, or magnetic-tape reader, or the like). When in the idle, but ready-to-operate, condition; all of the locking armatures 18 of the locking magnets 17 are deenergized, and the electromagnetic driving shaft 2 rotates in the direction as indicated by the arrow, but is deenergized. in this way all type rings 1, which are now in the unblocked condition, and which are even slightly braked or retarded via the ratchet wheels 8 by the act-ion of the brushes 15, are hardly taken along, because the slight friction of the type rings 1 on the electromagnetic driving shaft 2 is insufficient for effecting a coupling. The aligning-beam coils 21 and 22, are likewise deenergized. The letters and figures to be printed are prepared via the input device in the relay circuit, for example, in a 4-out-of-8 code, i.e. in such a way that the looking magnets 17 are only attracted in a relay position corresponding to the previously prepared setting. When the printing is supposed to be performed, the electromagnetic driving shaft '2 is energized and causes a rotation of the type rings 1 and of the associated ratchet wheels 8.

Since the setting of the relay circuit is effected by the pulse-transmitting disk 14, all of the existing combinations are now successively set in the course of one complete rotation of this disk. The circuit of the locking magnet 17 is completed as soon as the prepared combination is found, and the ratchet wheel 8 is stopped by the action of the locking armature 18. By the action of an additional hold contact provided at the locking magnet 17 this condition can be retained until performing the printing process. Thereupon. an interruption of the common current supply causes all of the locking armatures 18 to drop off, and permits all ratchet wheels 8 to rotate freely again.

After the disengagement of all locking armatures 18, which may be supervised electrically by providing a further test contact at the locking magnet 17 (not shown), the electromagnetic driving shaft 2 is deenergized and the aligning-beam coils 21 and 22 are energized. This causes the electromagnetic friction to be removed completely, the locking armatures 18 to be disengaged, and

the type rings 1 to be retained in their position only by the action of the two pole pieces '19 and 29. Thereupon the printing is effected in that the printing beam 25 either is moved jerkily upwards, or pressed in the upward direction. After the printing operation the coils 21 and 22 are deenergized, so that now the type rings 1 and the ratchet wheels 8 are again permitted to move freely. Since immediately after the elimination of the electromagnetic friction a new line may be prepared, it is possible to initiate the new setting and printing process immediately after the performance of the preceding printing process.

While I have described above the principles of my invention in connection with specific apparatus, it is .to be clearly understood that this description is made only by way of example and not as a limitation to the scope of my invention as set forth in the objects thereof and in the accompanying claims.

What is claimed is:

1. A line-at-a-time printer comprising an electromagnetic shaft, means for rotating said shaft, a plurality of type rings having types spaced apart to form gaps therebetween loosely seated on said shaft and adapted to be rotated with said shaft by magnetic torque at any angular position of said type rings with respect to said shaft when said electromagnetic shaftis energized, a toothed ratchet wheel for each type ring rotatably mounted on an axis spaced'from the axis of said shaft, the teeth of said ratchet wheel being so spaced as to mesh with the gaps between the types of said type ring, whereby rotation .of each type ring will rotate its associated ratchet Wheelja 'ratchet pawl for each ratchet wheel mounted for movement into and out of engagement with its associated wheel and so positioned as to hold said wheel against further rotation with the associated type ring in proper printing position when said pawl is moved into engagement with said wheel.

2. A line-at-a-time printer, as defined in claim 1, in which an electromagnet' having an armature is provided for each ratchet wheel and in which said armature is itself the ratchet pawl which engages the ratchet wheel.

3. A line-at-a-time printer, as defined in claim 2, further comprising means for energizing the pawl-operating electromagnets at selected positions of the associated ratchet wheels, said means comprising a code disk on each ratchet wheel and a set of sensing elements for each code disk adapted to engage said disk and to complete a circuit through the associated electromagnet when a selected position is reached.

4. A lineat-a-time printer, as defined in claim 1.

furthercomprising means for moving the pawl associated with a ratchet wheel into engagement with said wheel, said means comprising a code disk on each ratchet wheel and a set of sensing elements adapted to engage said disk.

References Cited in the file of this patent UNITED STATES PATENTS 'Fender et a1. July 25, 

1. A LINE-AT-A-TIME PRINTER COMPRISING AN ELECTROMAGNETIC SHAFT, MEANS FOR ROTATING SAID SHAFT, A PLURALITY OF TYPE RINGS HAVING TYPES SPACED APART TO FORM GAPS THEREBETWEEN LOOSELY SEATED ON SAID SHAFT AND ADAPTED TO BE ROTATED WITH SAID SHAFT BY MAGNETIC TORQUE AT ANY ANGULAR POSITION OF SAID TYPE RINGS WITH RESPECT TO SAID SHAFT WHEN SAID ELECTROMAGNETIC SHAFT IS ENERGIZED, A TOOTHED RATCHET WHEEL FOR EACH TYPE RING ROTATABLY MOUNTED ON AN AXIS SPACED FROM THE AXIS OF SAID SHAFT, THE TEETH OF SAID RATCHET WHEEL BEING SO SPACED AS TO MESH WITH THE GAPS BETWEEN THE TYPES OF SAID TYPE RING, WHEREBY ROTATION OF EACH TYPE RING WILL ROTATE ITS ASSOCIATED RATCHET WHEEL, A RATCHET PAWL FOR EACH RATCHET WHEEL MOUNTED FOR MOVEMENT INTO AND OUT OF ENGAGEMENT WITH ITS ASSOCIATED WHEEL AND SO POSITIONED AS TO HOLD SAID WHEEL AGAINST FURTHER ROTATION WITH THE ASSOCIATED TYPE RING IN PROPER PRINTING POSITION WHEN SAID PAWL IS MOVED INTO ENGAGEMENT WITH SAID WHEEL. 